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The molar heat capacity of 1,4-bis(3-methylimidazolium-1-yl)butane bis(trifluoromethylsulfonyl)imide dicationic ionic compound ([C4(MIm)2][NTf2]2) has been studied over the temperature range from 6 to 350 K by adiabatic calorimetry. In the above temperature interval, this compound has been found to form crystal, liquid, and supercooled liquid. For [C4(MIm)2][NTf2]2, the temperature of fusion T°fus = (337.88 ± 0.01) K has been determined by the fractional melting experiments, the enthalpy of fusion ΔfusH° = (52.79 ± 0.28) kJ mol−1 has been measured using the calorimetric method of continuous energy input, and the entropy of fusion ΔfusS° = (156.2 ± 1.7) J K−1 mol−1 has also been evaluated. The standard thermodynamic functions of the studied dicationic ionic compound, namely, the heat capacity Cp°(T), the enthalpy [H°(T) − H°(0)], the entropy S°(T) and the Gibbs free energy [G°(T) − H°(0)] have been calculated on the basis of the experimental data for the temperature range up to 350 K. The results have been discussed and compared with those available in the literature and in the NIST Ionic Liquids Database (ILThermo) for monocationic ionic compounds. [ABSTRACT FROM AUTHOR]

The heat capacity of palladium bis-hexafluoroacetylacetonate (Pd(C5HF6O2)2; CAS no. 64916-48-9) is measured adiabatically in the range of 6.088–307.596 K. The obtained data are used to calculate thermodynamic functions (entropy, increment of enthalpy, reduced Gibbs energy) in the range of 0–310 K. The functional behavior of the heat capacity exhibits an anomaly in the range of 145–285 K. The anomaly has a maximum at a temperature of T ≈ 225 K, indicating a second-order phase transition in this range of temperatures. Anomalous contributions to entropy and enthalpy are calculated. [ABSTRACT FROM AUTHOR]

The heat capacity of copper bis-dipivaloylmethanate complex (Cu(C11H19O2)2 or Cu(dpm)2; CAS no. 14040-05-2) in the 5.440–313.271 K range of temperatures is measured via adiabatic calorimetry. The functional behavior of the heat capacity in the studied range of temperatures does not exhibit any anomaly that could be attributed to phase transitions. The heat capacity data are used to calculate entropy, enthalpy increment, and reduced Gibbs energy in the 0–310 K range of temperatures. Based on this analysis, a universal description of heat capacity is proposed for metal dipivaloylmethanates in a wide range of temperatures. The description can be used to calculate the thermodynamic characteristics of objects from this isoligand group of metal beta-diketonates that have yet to be studied. [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical studies investigating the impact of three curing conditions on temperature evolution in concrete cubes. The tests were performed on samples of the same volume (3.375 dm3) under different curing conditions: room temperature, insulation boxes, and adiabatic calorimeter. Various cements (Portland cement, Portland composite cement, and blast furnace slag cement) and aggregates (gravel and basalt) were examined. The temperature evolution for all mixtures was analyzed, revealing a correlation between temperature increase and concrete type. Under insulation and adiabatic curing, Portland cement with gravel aggregate exhibited the highest temperature rise, while blast furnace slag cement with basalt aggregate showed the lowest increase. The incorporation of slag, ash, or other mineral additives reduced temperature rise. Additionally, basalt aggregate's higher heat capacity and thermal energy accumulation led to a decreased temperature increase compared to gravel. Using recorded thermal data, a numerical procedure predicting temperature development in nonadiabatic conditions through direct adiabatic tests is proposed. Comparisons between experimental and numerical temperature evolutions confirmed the model's accuracy. [ABSTRACT FROM AUTHOR]

Heat capacity of tris-lanthanum heptafluorodimethyloctanedionate (La(C10H10F7O2)3; CAS no. 19106-89-9) has been measured by the adiabatic method in the range from 10.88 to 300.60 K. Based on the data obtained, the values of thermodynamic functions (entropy, enthalpy increment, and reduced Gibbs energy) have been calculated in the temperature range from 0 to 300 K. As a result of the analysis of the functional behavior of the heat capacity, an anomaly has been revealed in the range of 36–110 K with a maximum at temperature T ≈ 80 K, which indicates the presence of a phase transition in this temperature range. Anomalous contributions to entropy and enthalpy are identified. The possible cause of the detected phase transition has been considered. [ABSTRACT FROM AUTHOR]

The molar heat capacity of 1,4-bis(3-methylimidazolium-1-yl)butane bis(trifluoromethylsulfonyl)imide dicationic ionic compound ([C4(MIm)2][NTf2]2) has been studied over the temperature range from 6 to 350 K by adiabatic calorimetry. In the above temperature interval, this compound has been found to form crystal, liquid, and supercooled liquid. For [C4(MIm)2][NTf2]2, the temperature of fusion T°fus = (337.88 ± 0.01) K has been determined by the fractional melting experiments, the enthalpy of fusion ΔfusH° = (52.79 ± 0.28) kJ mol−1 has been measured using the calorimetric method of continuous energy input, and the entropy of fusion ΔfusS° = (156.2 ± 1.7) J K−1 mol−1 has also been evaluated. The standard thermodynamic functions of the studied dicationic ionic compound, namely, the heat capacity Cp°(T), the enthalpy [H°(T) − H°(0)], the entropy S°(T) and the Gibbs free energy [G°(T) − H°(0)] have been calculated on the basis of the experimental data for the temperature range up to 350 K. The results have been discussed and compared with those available in the literature and in the NIST Ionic Liquids Database (ILThermo) for monocationic ionic compounds.

The low-temperature behavior of the heat capacity and photoluminescence of the earlier structurally characterized binuclear pivalate complex [Eu2(Bath)2(Piv)6] (monoclinic crystal system, I2/a) (I), where Bath = 4,7-diphenyl-1,10-phenanthroline, Piv = , is studied. The temperature dependence of the heat capacity in a temperature range of 5.96–302.88 K is measured by adiabatic calorimetry, and the thermodynamic functions (T), S°(T), Ф°(Т), and Н°(Т) – Н°(0) are calculated. The absence of low-temperature phase transitions in complex I is shown. In a temperature range of 98–295 K, complex I demonstrates a high temperature stability of the integral photoluminescence intensity of the 5D0–7Fj (j = 0–6) transitions of the Eu3+ ion. [ABSTRACT FROM AUTHOR]

The low-temperature behavior of the heat capacity and photoluminescence of the earlier structurally characterized binuclear pivalate complex [Eu2(Bath)2(Piv)6] (monoclinic crystal system, I2/a) (I), where Bath = 4,7-diphenyl-1,10-phenanthroline, Piv = , is studied. The temperature dependence of the heat capacity in a temperature range of 5.96–302.88 K is measured by adiabatic calorimetry, and the thermodynamic functions (T), S°(T), Ф°(Т), and Н°(Т) – Н°(0) are calculated. The absence of low-temperature phase transitions in complex I is shown. In a temperature range of 98–295 K, complex I demonstrates a high temperature stability of the integral photoluminescence intensity of the 5D0–7Fj (j = 0–6) transitions of the Eu3+ ion. [ABSTRACT FROM AUTHOR]

Thermodynamic properties of polycrystalline powders of ruthenium dichalcogenides have been studied using calorimetric isobaric heat capacity measurements in a wide temperature range. The adiabatic and differential scanning calorimetry data for ruthenium disulfide and ruthenium diselenide have been used to determine standard thermodynamic functions (heat capacity, entropy, enthalpy increment, and reduced Gibbs energy) of these compounds in the range 10–965 K. At 298.15 K, the functions of RuS2 are as follows: = 60.82 ± 0.12 J/(K mol), S° = 56.05 ± 0.11 J/(K mol), Н°(298.15 K) − Н°(0) = 9.75 ± 0.02 kJ/mol, and Ф° = 23.34 ± 0.05 J/(K mol). For RuSe2, we have obtained = 69.96 ± 0.14 J/(K mol), S° = 80.62 ± 0.16 J/(K mol), Н°(298.15 K) − Н°(0) = 13.05 ± 0.03 kJ/mol, and Ф° = 36.85 ± 0.08 J/(K mol). The data obtained above 298 K have been used to determine empirical coefficients of the Maier–Kelley and Khodakovsky equations. The absolute entropies obtained in this study for the ruthenium dichalcogenides, in combination with literature data, have made it possible to evaluate the Gibbs energy of formation of RuS2(cr) and RuSe2(cr) at 298.15 K. [ABSTRACT FROM AUTHOR]

In this work, we present a comprehensive study of the thermodynamic properties of 3-and 4-ethoxyacetanilides. The heat capacities in crystalline, liquid, and supercooled liquid states from 80 to 475 K were obtained using adiabatic, differential scanning (DSC), and fast scanning (FSC) calorimetries. The fusion enthalpies at Tm were combined from DSC measurement results and the literature data. The fusion enthalpies at 298.15 K were evaluated in two independent ways: adjusted according to Kirchhoff's law of thermochemistry, and using Hess' law. For the latter approach, the enthalpies of the solution in DMF in crystalline and supercooled liquid states were derived. The values obtained by the two methods are consistent with each other. The standard thermodynamic functions (entropy, enthalpy, and Gibbs energy) between 80 and 470 K were calculated. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis of crystalline ruthenium ditelluride (RuTe2) and its thermodynamic properties in the range from 10 to 965 K, evaluated from its isobaric heat capacity Cp determined using calorimetry. At low temperatures, between 6.86 and 335.11 K, the heat capacity of the synthesized material—pure, free of impurities and foreign phases—was determined by adiabatic calorimetry. In the range 315.3–965.3 K, Cp was determined by differential scanning calorimetry. The data obtained above 298 K have been used to determine empirical coefficients of the Maier–Kelley and Khodakovsky equations. In the range 10–965 K, we have evaluated the standard thermodynamic functions: heat capacity, entropy, enthalpy increment, and reduced Gibbs energy. At 298.15 K, we have obtained = 72.43 ± 0.14 J/(K mol), S° = 94.94 ± 0.19 J/(K mol), Н°(298.15 K) − Н°(0) = 14.60 ± 0.03 kJ/mol, and Ф° = 45.97 ± 0.09 J/(K mol). Using the absolute entropy determined by us and data in the literature and handbooks, we have estimated the standard Gibbs energy of formation of RuTe2: ΔfG°(RuTe2, cr, 298.15) = −130.5 ± 2.9 kJ/mol. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis of crystalline platinum ditelluride, PtTe2, a synthetic analog of the mineral moncheite, and its thermodynamic properties. Using the isobaric heat capacity of PtTe2 determined in the range 2–305 K by the relaxation and adiabatic calorimetry methods, we have evaluated its standard thermodynamic functions: entropy, enthalpy increment, and reduced Gibbs energy. The following parameters have been obtained for PtTe2 at 298.15 K: = 75.11 ± 0.15 J/(K mol), S° = 121.5 ± 0.2 J/(K mol), Н°(298.15 K) − Н°(0) = 16.69 ± 0.03 kJ/mol, and Ф° = 65.55 ± 0.13 J/(K mol). Using data in the literature and handbooks, we have estimated the standard Gibbs energy of formation of PtTe2: ΔfG°(PtTe2, cr, 298.15) = –75.4 ± 0.8 kJ/mol. Fractal analysis of the heat capacity data indicates that PtTe2 has a layered structure and that its Debye temperature is 250 K. [ABSTRACT FROM AUTHOR]

It is of much interest to study the heavy hydrocarbon impact on the phase behavior of hydrocarbons. Using a method of the precision adiabatic calorimetry the phase equilibria in quaternary mixtures of methane, propane, octane, and nonane have been studied. The phase diagrams for investigated mixtures have been plotted based on the experimental data. The phase transitions were localized by the finite discontinuities in temperature derivatives of the thermodynamic potentials. The heat capacity, internal energy, pressure, and temperature derivative of pressure at constant volume were measured in the range 170–320 K, up to 40 MPa. Quaternary mixtures as quasi-binary mixtures are presented. The first quasi-component of the quasi-binary mixture is the binary mixture with the constant methane/propane ratio. The second quasi-component of the quasi-binary mixture is the binary mixture of octane and nonane. Investigated hydrocarbon system is the combination of the simple hydrocarbon mixtures for the low concentration of octane and nonane. In the earlier papers we presented the simple hydrocarbon mixtures for the low concentration of octane, nonane, and decane, and quaternary mixtures of methane, propane, octane, and decane for the low concentration of octane and decane, which are the combination of the simple hydrocarbon mixtures for the low concentration of octane and decane. Our investigations show that quaternary hydrocarbon mixture for the low concentration of octane and nonane as well as the simple hydrocarbon mixtures for the low concentration of octane, nonane, and decane split into three phases, the macrophase composed of methane, propane, octane, and nonane, and two microphases formed by octane and nonane. In this system octane and nonane dissolved in the macrophase partly. Besides, the heavy components provoke a split of the liquid part of the quaternary mixture into two liquid phases. [ABSTRACT FROM AUTHOR]

The availability of sufficient amounts of form I of benzocaine has led to the investigation of its phase relationships with the other two existing forms, II and III, using adiabatic calorimetry, powder X-ray diffraction, and high-pressure differential thermal analysis. The latter two forms were known to have an enantiotropic phase relationship in which form III is stable at low-temperatures and high-pressures, while form II is stable at room temperature with respect to form III. Using adiabatic calorimetry data, it can be concluded, that form I is the stable low-temperature, high-pressure form, which also happens to be the most stable form at room temperature; however, due to its persistence at room temperature, form II is still the most convenient polymorph to use in formulations. Form III presents a case of overall monotropy and does not possess any stability domain in the pressure–temperature phase diagram. Heat capacity data for benzocaine have been obtained by adiabatic calorimetry from 11 K to 369 K above its melting point, which can be used to compare to results from in silico crystal structure prediction. [ABSTRACT FROM AUTHOR]

The recent results of the accurate calorimetric measurements of phase equilibria in ternary mixtures of methane, propane, and nonane have been presented. The heat capacity, internal energy, pressure, and temperature derivative of pressure at constant volume were measured in the range 160–340 K, up to 30 MPa. The phase transitions were localized by the finite discontinuities in temperature derivatives of the thermodynamic potentials. The phase diagrams for ternary mixtures of methane, propane, and nonane have been plotted based on the experimental data. These data are supplemented with the earlier measurements of two ternary hydrocarbon systems for the low concentration of octane and decane. Our investigations show that hydrocarbon mixture for the low concentration of nonane as well as the hydrocarbon mixtures for the low concentration of octane and decane split into two phases, the nonane-lean macrophase and the microphase formed by nonane. Besides, nonane provokes a split of the liquid part of a ternary mixture into two liquid phases, the nonane-rich phase and the nonane-lean phase. [ABSTRACT FROM AUTHOR]

Water in a crosslinked dextran gel, Sephadex® G25, is known to remain partially unfrozen during cooling and undergoes ice crystallization during rewarming. However, the mechanism of ice crystallization during rewarming is still unclear. To elucidate the frozen state of water in the gel, thermal behavior at low temperatures was investigated by using adiabatic calorimetry. Heat capacities and enthalpy-relaxation rates of the gel-containing water of mass ratio h (=g H2O/g dry G25) = 1.00 were measured between 80 and 300 K during rewarming, where the gel was intermittently heated at the rate of 50–100 mK min−1. Although an exotherm indicating ice crystallization during rewarming was confirmed with the gel precooled rapidly, at 5 K min−1, it disappeared when precooled slowly, at 20 mK min−1. During rewarming after the rapid cooling, two glass transitions were observed at ca. 175 K and 240–242 K. A higher-temperature glass transition due to the water trapped by the polymer network was not so clear, as it was overlapped with an endotherm due to the melting of small ice crystals, which indicates that the ice crystals formed have a broad size-distribution and that water in the gel is vitrified when ice crystals of even the smallest size cannot be formed. [ABSTRACT FROM AUTHOR]

• Heat capacities of compounds in the range (5–370) K were measured for the first time. • Thermal stability and melting parameters of compounds were determined using DSC+TGA. • Thermodynamic properties in the range of (0 – T m) K were calculated. • Thermodynamic properties of compounds explained with their structure. In this paper, we present the results of comprehensive thermodynamic study of some functionally substituted triazoles such as 1-benzyl-4-phenyl-1 H -1,2,3-triazole, 1-benzyl-4-(m -tolyl)-1 H -1,2,3-triazole and 1-benzyl-4-(4‑ tert -butylphenyl)-1 H -1,2,3-triazole. The temperature dependences of heat capacities of 1-benzyl-4-(m -tolyl)-1 H -1,2,3-triazole and 1-benzyl-4-(4‑ tert -butylphenyl)-1 H -1,2,3-triazole were measured in a wide temperature range of ∼(5 – 370) K using the adiabatic calorimetry. Those of 1-benzyl-4-phenyl-1 H -1,2,3-triazole were determined at the range of ∼(5 – 80) K, supplementing the previous measurements at the more elevated temperatures. The melting parameters and thermal stability (melting temperature, enthalpy of fusion, temperature of thermal destruction) of the compounds were determined using the differential scanning calorimetry. Also, the standard thermodynamic functions (absolute entropies, reduced enthalpies and Gibbs energies) were calculated in the temperature range of (0 – T m) K. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, we present a comprehensive study of the thermodynamic properties of 3-and 4-ethoxyacetanilides. The heat capacities in crystalline, liquid, and supercooled liquid states from 80 to 475 K were obtained using adiabatic, differential scanning (DSC), and fast scanning (FSC) calorimetries. The fusion enthalpies at Tm were combined from DSC measurement results and the literature data. The fusion enthalpies at 298.15 K were evaluated in two independent ways: adjusted according to Kirchhoff’s law of thermochemistry, and using Hess’ law. For the latter approach, the enthalpies of the solution in DMF in crystalline and supercooled liquid states were derived. The values obtained by the two methods are consistent with each other. The standard thermodynamic functions (entropy, enthalpy, and Gibbs energy) between 80 and 470 K were calculated.

This paper is focused on the effect of hydrogen peroxide (H2O2) on the thermal decomposition of N–methylmorpholine–N–oxide (NMMO). First, accelerating rate calorimetry (ARC) was used to investigate the thermal characteristics of NMMO/H2O2 with different molar ratios. It was found that "onset" temperature was reduced to the minimum temperature with 391.67 K as the molar ratio of NMMO/H2O2 was 3:1. Second, the main decomposed products of NMMO and NMMO/H2O2 were 4–methylmorpholine (NMM) and morpholine (M) identified by liquid chromatography-mass spectrometry (LC–MS). The presence of H2O2 was beneficial to generate more M. Finally, microreactor calorimetry (C80) was employed to calculate the time to maximum rate (TMRad) and the temperature as TMRad is 24 h combined with Friedman and Flynn–Wall–Ozawa models during the decomposition of NMMO and NMMO/H2O2 (molar ratio of 3:1). The apparent activation energy (Ea,ARC) of pure NMMO with 274.99 kJ mol−1 was higher than that of NMMO in the mixture (NMMOmix) with 123.71 kJ mol−1. Besides, TMRad,s of NMMOmix decreased from 39.77 to 27.96 min, and no obvious decrease of TD24 was found compared with the pure NMMO. The results indicated that the presence of H2O2 increased the risk of thermal runaway of NMMOmix, and the mixture had the worst thermal stability as the molar ratio of NMMO/H2O2 was 3:1. It was worthy of mentioning that the most hazardous moment was not the dosing end, but the generated NMMO and H2O2 was reached to 3:1 in the synthesis of NMMO. [ABSTRACT FROM AUTHOR]

Solid-phase samples with the general formula Ba(La,Gd)2WO7 are synthesized in ternary oxide systems based on barium, lanthanum, gadolinium, and tungsten. Full-profile calculations of X-ray diffractograms are used to refine unit cell parameters and estimate the content of additional phases. Adiabatic calorimetry is used to investigate the temperature dependence of samples' heat capacity in the helium range (4.25–325 K) and record anomalies caused by the doping element. The experimental heat capacities are corrected for the content of impurity compounds. Experimental data are used to reveal the lattice component of the heat capacity and calculate thermodynamic functions of the compounds in the range of 5–320 K, in order to determine changes in entropy and enthalpy in the domain of anomalies. The standard values of the Ba(La Gdx)2WO7 thermodynamic functions are found to be x = 0.01, 0.03, and 0.05: = 190.9 ± 1.5, 198.6 ± 1.5, and 207.0 ± 1.5 J/(mol K); = 221.3 ± 12.9, 229.6 ± 13.3, and 229.1 ± 13.4 J/(mol K); and – = 34 161 ± 1379, 35 389 ± 1430, and 35 511 ± 1429 J/mol, respectively. [ABSTRACT FROM AUTHOR]

Precision adiabatic vacuum and differential scanning calorimetry are used to study he temperature dependence of the heat capacity of a copolymer of poly(1-hydroxyimino)trimethylene and poly(1-hydroxyimino-3-methyl)trimethylene with a 23.4 mol % concentration of propane fragments in the range of 6 to 430 K. Its standard thermodynamic functions H°(T)–H°(0), S°(T)–S°(0), and G°(T)–H°(0) for the range of T → 0 to 400 K are calculated using the obtained experimental data. The thermodynamic properties of the copolymer are compared to those of a corresponding polyketone studied earlier and poly(1-hydroxyimino)trimethylene. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry is used to study the temperature and enthalpy of melting of L‑asparagine monohydrate. Its thermal stability is estimated. Low-temperature adiabatic calorimetry is used to measure heat capacity in the 8–355 K range of temperatures. An anomaly in the heat capacity curve is detected in the region of 265–275 K and studied. A single crystal X-ray diffraction study of the sample is performed in the 113–281 K range of temperatures. The main thermodynamic functions and the functions of formation in the condensed state are calculated at 298 K using the experimental and literature data. [ABSTRACT FROM AUTHOR]

A method was proposed for preparing magnesium indate, and its thermodynamic properties were studied experimentally. MgIn2O4 powder was prepared by high-temperature annealing of a mixture of nanocrystalline indium oxide and magnesium oxide. The mixture was prepared by the thermal decomposition of a gel-like precursor comprising glycine and magnesium and indium nitrates. The microstructure, phase and chemical compositions of the powder produced by high-temperature annealing were studied by scanning electron microscopy, X-ray powder diffraction (XRD), and X-ray fluorescence spectrometry (XFS). The temperature-dependent heat capacity of MgIn2O4 was measured by relaxation calorimetry (RC), adiabatic calorimetry (AC), and differential scanning calorimetry (DSC) at temperatures from 4.2 to 1346 K. The experimental heat capacity curve in the range of temperatures studied shows no anomalies. The measured heat capacities were used to calculate temperature-dependent standard thermodynamic functions of MgIn2O4 in the range from 0 to 1346 K. [ABSTRACT FROM AUTHOR]

This study focused on the assessment of thermal safety associated with the synthesis of N-methylmorpholine-N-oxide (NMMO), a reaction known to be hazardous. First, a reaction calorimeter (SIMULAR) was used to investigate the exothermic behavior of the reaction in the semi-batch operation. The overall heat of the synthesis of 121.69 kJ mol−1 (based on the molar of N-methylmorpholine) and the maximum temperature of the synthesis reaction (MTSR) of 352.71 K under uncontrolled conditions were derived from calorimetric data and high-performance liquid chromatography results. Second, the thermal decomposition of H2O2/NMMO and NMMO under non-isothermal and adiabatic conditions and the possibility of secondary decomposition under runaway conditions were analyzed by differential scanning calorimetry and accelerating rate calorimetry to calculate the time to maximum rate (TMRad) and the temperature as TMRad is 24 h. The heat of decomposition of NMMO ranged from 314.23 to 416.23 J g−1. The activation energy (Ea), calculated using the kinetics method under non-isothermal conditions, was 40–89 kJ mol−1, which was lower than that derived under adiabatic conditions. Furthermore, the TD24 of H2O2/NMMO was lower than that of NMMO owing to the coupling effect. Finally, the risk assessment of thermal runaway was conducted on the basis of the Stoessel criticality diagram. The results indicated that the synthesis of NMMO has a class 2 risk level. Although the risk of the synthetic reaction is low, there are still hidden dangers such as thermal hazards during the NMMO synthesis in the presence of H2O2. [ABSTRACT FROM AUTHOR]

Precision adiabatic vacuum and differential scanning calorimetry are used to study the thermodynamic properties of a carbon monoxide terpolymer in the interval 6–525 K. The material consists of ethylene and butene-1 with 35 mol % butane units. The temperature dependence of the heat capacity is determined in the interval 6–350 K, along with the thermodynamic properties of devitrification and the temperature and enthalpy of melting. Standard thermodynamic functions are calculated from Т → 0 to 350 K: , H°(T)–H°(0), S°(T)–S°(0), and G°(T)–H°(0). Conclusions are reached in regard to the topological structure of the terpolymer, based on a multifractal model of processing the low-temperature heat capacity. The obtained data are compared to the available thermodynamic properties of similar terpolymers of other compositions. [ABSTRACT FROM AUTHOR]

The phase behavior of quaternary mixtures of methane, propane, octane, and decane for the low concentration of heavy hydrocarbons (octane and decane) are qualitatively transformed compared to the customary concept. Each mixture splits into three phases, a macroscopic phase enriched by methane and propane and two microscopic phases enriched by octane or decane. Each microphase consists of one heavy component. The microphase phase behavior depends on the composition of the macrophase. If octane dissolves in the macrophase the line of formation of the decane-rich microphase shifts to the lower temperature. The heavy hydrocarbons provoke a split of the liquid part of the macrophase into two liquid phases. All phases are equilibrium phases. Based on the quasi-binary approximation the hydrocarbon mixtures for the low concentration of heavy components are prepared. The first quasi-component is a binary mixture with the constant methane/propane ratio. The second quasi-component is octane and decane. [ABSTRACT FROM AUTHOR]

Pressure and temperature play an important role in the adiabatic decomposition of hazardous materials. In this article, Accelerating Rate Calorimeter (ARC) was used to study adiabatic decomposition of 40 wt% dicumyl peroxide (DCP) solution 20 wt% di-tert-butyl peroxide (DTBP) solution and 2,4-dinitrotoluene (2,4-DNT). Based on the temperature and pressure signals, the kinetic constants of 40 wt% DCP and20 wt% DTBP were calculated separately. It is found that the temperature and gas production kinetics of the 40 wt% DCP solution are in good agreement with each other, but the temperature and gas production kinetics of 20 wt% DTBP solution are significantly different. The adiabatic decomposition of 2,4-DNT under different pressure conditions was experimentally investigated. The experimental results indicated that pressure promoted the adiabatic decomposition of 2,4-DNT. Accordingly, new kinetic equations were developed to describe the adiabatic decomposition of 2,4-DNT under different pressure conditions. These works provide a new insight into adiabatic kinetics calculations. [ABSTRACT FROM AUTHOR]

• The temperature and pressure coupling problem was solved in adiabatic system. • The process of gas and heat production may be the similar, but most are inconsistent. • The total pressure in system has a promoting effect on the thermal decomposition process of 2,4-DNT. • The kinetic equations with pressure terms can be used to describe reaction process at different pressures accurately. Pressure and temperature play an important role in the adiabatic decomposition of hazardous materials. In this article, Accelerating Rate Calorimeter (ARC) was used to study adiabatic decomposition of 40 wt% dicumyl peroxide (DCP) solution，20 wt% di-tert-butyl peroxide (DTBP) solution and 2,4-dinitrotoluene (2,4-DNT). Based on the temperature and pressure signals, the kinetic constants of 40 wt% DCP and20 wt% DTBP were calculated separately. It is found that the temperature and gas production kinetics of the 40 wt% DCP solution are in good agreement with each other, but the temperature and gas production kinetics of 20 wt% DTBP solution are significantly different. The adiabatic decomposition of 2,4-DNT under different pressure conditions was experimentally investigated. The experimental results indicated that pressure promoted the adiabatic decomposition of 2,4-DNT. Accordingly, new kinetic equations were developed to describe the adiabatic decomposition of 2,4-DNT under different pressure conditions. These works provide a new insight into adiabatic kinetics calculations. [ABSTRACT FROM AUTHOR]

Adiabatic calorimetry is one of the main experimental methods to quantitatively study the thermal hazard in chemical process. There are two problems in adiabatic calorimetry: (1) identification of the reaction model is difficult; (2) the equilibrium of system and the temperature uniformity of sample will be broken under the rapid temperature rise rate, especially at lower thermal inertia. In this work, the heat-quench-heat method in adiabatic calorimetry was proposed to determine the reaction model and slow the reaction rate to evaluate kinetic parameters accurately. A criterion was proposed to identify the reaction model which states that the decomposition is an n-order reaction if T0,stage1

Water in a crosslinked dextran gel, Sephadex® G25, is known to remain partially unfrozen during cooling and undergoes ice crystallization during rewarming. However, the mechanism of ice crystallization during rewarming is still unclear. To elucidate the frozen state of water in the gel, thermal behavior at low temperatures was investigated by using adiabatic calorimetry. Heat capacities and enthalpy-relaxation rates of the gel-containing water of mass ratio h (=g H2O/g dry G25) = 1.00 were measured between 80 and 300 K during rewarming, where the gel was intermittently heated at the rate of 50–100 mK min−1. Although an exotherm indicating ice crystallization during rewarming was confirmed with the gel precooled rapidly, at 5 K min−1, it disappeared when precooled slowly, at 20 mK min−1. During rewarming after the rapid cooling, two glass transitions were observed at ca. 175 K and 240–242 K. A higher-temperature glass transition due to the water trapped by the polymer network was not so clear, as it was overlapped with an endotherm due to the melting of small ice crystals, which indicates that the ice crystals formed have a broad size-distribution and that water in the gel is vitrified when ice crystals of even the smallest size cannot be formed.

The temperature dependence of the heat capacity of amorphous poly(1-(hydroxyimino)-2-phenyltrimethylene) was studied in the range 7–460 K by precision adiabatic vacuum and differential scanning calorimetry. The thermodynamic characteristics of its glass transition were determined. The standard thermodynamic functions , Н°(T) – H°(0), S°(T) – S°(0), and G°(T) – H°(0) for the region from Т → 0 to 415 K and the standard entropy of polymer formation at T = 298.15 K were calculated using the obtained experimental data. The thermodynamic properties of polystyrene oxime were compared with those of polystyrene ketone studied previously. [ABSTRACT FROM AUTHOR]

In adiabatic thermal analysis, correct measurement of temperature is usually ensured by means of a calibration procedure and thermal inertia corrections. However, there is a significant gradient within system, which not only makes the obtained test results inaccurate, but also causes serious errors in subsequent kinetic calculations and thermal risk assessment. Thus, estimations of the temperature gradients, which appear into the sample, are of highest interest to choose the right operational conditions that minimize that gradient. In this work, the CFD software has been applied to study this temperature gradient issue in adiabatic system. In view of the causes of temperature gradients, the influencing factors and the resulting analysis errors are all deeply researched. In addition, three different kinds of adiabaticity control model cases have also been simulated to explore the right operational conditions that minimize gradient and provide more reliable kinetics and thermal hazard parameters (Q∞, k0, Ea, n, TD24, TCL). After a comparative study, the authors define the more reliable operational conditions, which include selecting a suitable temperature response value and the adiabatic temperature control model. Finally, the reliability of the adiabaticity control model that achieves the minimum temperature gradients and provides the most accurate calculation results was verified through the different adiabatic tests. [ABSTRACT FROM AUTHOR]

Heat capacities of four ketohexoses, fructose, sorbose, psicose, and tagatose, were measured by adiabatic calorimetry in the temperature range from ca.10 to 330 K. For sorbose, thermal anomalies were detected: 199.5 K (main phase transition of order-disorder type), around 210 K (minor ones), and ca. 120 K (glass transition). Although no heat anomaly was observed for the other three ketohexoses, their standard thermodynamic functions were estimated from the measured molar heat capacities. A spectral analysis using Kieffer’s model was applied to the heat capacities to rationalize the relation among them in terms of intra- and intermolecular hydrogen bonds in crystal. [ABSTRACT FROM AUTHOR]

Samples based on strontium, lanthanum and tungsten with the general formula of Sr(La1-xLnx)2WO7 doped with samarium and europium at 1 and 3 at.% were synthesized by the solid-phase method at temperatures up to 1200 °C. The crystal structure of the samples was confirmed by X-ray powder diffraction. A full-profile refinement of the structure of compounds related to monoclinic syngony with the space group P1121/b was performed. The admixture phase is a compound of the Sr3Ln2W2O12 type with a trigonal system and space group . Based on the results of structure refinement, the ratio of the main compound and the admixture phase in the samples was determined to introduce corrections during measurements. Using adiabatic calorimetry we measured the heat capacity of the samples and found the thermodynamic functions of main compounds over the range of 5-320 K. Anomalies were detected in the heat capacity of the samples below 15 K, and we calculated the excess and lattice heat capacity for these anomalies by means of linearization methods. [ABSTRACT FROM AUTHOR]

In the present study, the molar heat capacity of solid formamidinium lead iodide (CH5N2PbI3) was measured over the temperature range from 5 to 357 K using a precise automated adiabatic calorimeter. In the above temperature interval, three distinct phase transitions were found in ranges from 49 to 56 K, from 110 to 178 K, and from 264 to 277 K. The standard thermodynamic functions of the studied perovskite, namely the heat capacity C°p(T), enthalpy [H0(T) − H0(0)], entropy S0(T), and [G°(T) − H°(0)]/T, were calculated for the temperature range from 0 to 345 K based on the experimental data. Herein, the results are discussed and compared with those available in the literature as measured by nonclassical methods.

As a result of citrate synthesis by the "sol–gel" method, we obtained samples of the compounds of ternary oxides with lanthanum, tungsten, and alkaline earth elements with the general formula MeLa2WO7 (Me = Mg, Ca, Sr, Ba). The structure of the samples obtained was studied by the X-ray diffraction, electron probe, and X-ray spectral microanalysis; the infrared and Raman spectra of the compounds were obtained. The results of indexing for SrLa2WO7 and BaLa2WO7 are in good agreement with the previously published crystallographic data. The heat capacity of the samples was measured by using of adiabatic calorimetry and their thermodynamic functions were calculated. [ABSTRACT FROM AUTHOR]

We have for the first time determined the temperature dependence of heat capacity for aurostibite, AuSb2, by adiabatic calorimetry and calculated its standard thermodynamic functions in a wide temperature range. At a temperature of 298.15 K, we have obtained = 76.01 ± 0.15 J/(mol K), S° = 133.4 ± 0.3 J/(mol K), Н°(298.15 K) − Н°(0)= 17.39 ± 0.03 kJ/mol, and Ф° = 75.02 ± 0.15 J/(mol K). Using previously reported data and the present results, we have found ΔfG°(298.15) = −11.36 ± 0.90 kJ/mol. [ABSTRACT FROM AUTHOR]

Thermodynamic properties (heat capacity Cp, entropy S°, enthalpy change ΔH° and reduced Gibbs energy ΔΦ°) of crystalline WO3 in a temperature range of 80–1256 K were refined using two complementary calorimetric methods, namely differential scanning calorimetry and adiabatic vacuum calorimetry. Enthalpy changes during a number of successive phase transitions in WO3 were calculated from differential scanning calorimetry data in both heating and cooling regimes and compared to previously reported values. For the first time, enthalpy changes for the orthorhombic to monoclinic and monoclinic to tetragonal high-temperature phase transitions in WO3 were estimated. [ABSTRACT FROM AUTHOR]

The decomposition of many hazardous materials goes through autocatalytic mechanisms. Due to the unpredictably sudden heat evolution companied with the decomposition of these materials, it is of great importance to identify autocatalytic decompositions and treat them with caution. In this work, a kinetic-parameters-free criterion is proposed to determine the autocatalytic decomposition using adiabatic calorimeters. This criterion states that the decompositions are autocatalytic if the values of R T p 2 T f − T p obtained by adiabatic experiments in different conditions are variable; otherwise they follow n-order behavior. Mathematical simulations at different values of φ , α 0 and T on have been conducted for n-order and autocatalytic decompositions to validate the criterion. To further validate the criterion, this method is applied to four representative substances: DCP, 20 % DTBP in toluene, BO and CHP. Overall, the validity of this criterion has been verified by simulation and experiment results. [ABSTRACT FROM AUTHOR]

The temperature-dependent heat capacity of vysotskite, PdS, has been determined for the first time by adiabatic, relaxation, and differential scanning calorimetry in a wide temperature range and standard thermodynamic functions of PdS have been calculated. The 298.15-K values thus obtained are = 43.65 ± 0.09 J/(mol K), S° = 51.98 ± 0.10 J/(mol K), Н°(298.15 К) − Н°(0) = 8.03 ± 0.02 kJ/mol, and Ф° = 25.03 ± 0.05 J/(mol K). Using the present results and data in the literature, we obtained ΔfH°(PdS, 298.15 K) = –74.0 ± 1.0 kJ/mol and ΔfG°(PdS, 298.15 K) = –68.7 ± 1.0 kJ/mol. [ABSTRACT FROM AUTHOR]

X-ray diffraction and high-resolution adiabatic calorimetry have been used to study the polymorphic behaviour of 75OBC liquid crystal. On heating of 75OBC from the room temperature, the crystal phase (Cr-I) melts directly to smectic A (Sm-A) and then to isotropic phase. On cooling from isotropic phase the 75OBC undergoes successive transitions to Sm-A, hexatic B (Hex-B), crystalline (Cr-II) phases, and next to another crystal phase – Cr-III. The latter two crystalline phases were shown to relax slowly to Cr-I phase, which is stable at low temperatures. X-ray data indicate that the Cr-II phase possesses orthorhombic lattice with herringbone in-plane order of the molecules (Cr-E). The Cr-I and Cr-III phases belong to different low symmetry monoclinic lattices. Our results demonstrate a complex polymorphism of 75OBC compound: the thermodynamic pathway that involves monotropic Hex-B and orthorhombic Cr-E phases corresponds to a local thermodynamic minimum, while the other ones showing melting from the Cr-I to Sm-A phase belongs to the global minimum. The similar thermal behaviour was observed for other members of nmOBC homologous series, possessing a Sm-A – Hex-B – Cr-E phase sequence on cooling. The 75OBC polymorphic behaviour is discussed in terms of molecular packing and stability of Cr-E orthorhombic lattice that precedes the transition to the Hex-B phase. [ABSTRACT FROM AUTHOR]

Samples of compounds were synthesized by the solid-phase method from the systems of barium, lanthanum, europium, and tungsten ternary oxides with the general formula Ba(La,Eu)2WO7. The unit cell parameters were refined, and the content of additional phases was determined using the full-profile calculation of X-ray diffraction patterns. The heat capacities of these samples were studied by adiabatic calorimetry from the helium region to room temperatures (4.25–315 K), and the anomalies produced by the doping element were detected. Based on the experimental data, the lattice component of the heat capacity was recognized to determine the entropy and enthalpy changes in the anomalies, and the thermodynamic functions of the compounds were calculated within a range of 5–310 K. The standard thermodynamic functions are Cp,298.15 = 208.3 ± 0.7 J/(mol K), = 243.6 ± 1.5 J/(mol K), and H298.15 – H0 = 37360 ± 185 J/mol for Ba(La0.99Eu0.01)2WO7, Cp,298.15 = 208.7 ± 0.5 J/(mol K), = 244.0 ± 1.2 J/(mol K), and H298.15 – H0 = 37619 ± 142 J/mol for Ba(La0.97Eu0.03)2WO7, and Cp,298.15 = 208.8 ± 0.8 J/(mol K), = 242.6 ± 1.5 J/(mol K), and H298.15 – H0 = 37384 ± 190 J/mol for Ba(La0.95Eu0.05)2WO7. [ABSTRACT FROM AUTHOR]

The present work shows the accurate calorimetric measurements of phase equilibria of hydrocarbon mixtures for the low concentration of heavy hydrocarbon components in particular the system methane + propane + decane with special emphasis on the concentration of decane below one mole percentage. Heat capacity, internal energy, pressure, and temperature derivative of pressure at constant volume for the ternary system have been measured in the range of 100–370 K and 0.1–40 MPa. To show a procedure of the phase diagram plotting by a precision adiabatic calorimetry, the typical phase diagram for a hydrocarbon mixture has been plotted in detail. A phase diagram has been plotted based on the experimental data of heat capacity, internal energy, pressure, and temperature derivative of pressure at constant volume. A phase transition is localized by a finite discontinuity in a temperature derivative of the thermodynamic potential. A closed area surrounded by the typical phase envelope for a pressure–temperature diagram is the two-phase region. Our particular attention is paid to the ternary system methane + propane + heavy hydrocarbon component for the low concentration of heavy hydrocarbon, in particular, of decane, due to the fact the conventional PVT approach does not guarantee the efficiency and accuracy of the phase diagram plotting for this system. Our investigations show the phase behavior of a hydrocarbon mixture for the low concentration of decane is drastically transformed compared to the customary concept. The hydrocarbon mixture splits into two phases, a macrophase enriched by methane and propane (a decane-poor phase) and a decane-rich microphase. To prove that all phases are equilibrium phases, a cooling mode of measurements is used. At the cooling mode of measurements, the same phase transitions as at the heating mode occur. These phase transitions correspond to the formation of a decane-rich microphase and a macrophase enriched by methane and propane. [ABSTRACT FROM AUTHOR]

The thermodynamic properties of crystalline platinum disulfide have been studied in the range from 5 to 875 K. The isobaric heat capacity of PtS2 has been determined by two methods: by adiabatic calorimetry from 5.32 to 344.96 K and by differential scanning calorimetry in the range 344.6–874.6 K. Using the experimental Cp(T) data, we evaluated the standard thermodynamic functions of platinum disulfide in a wide temperature range. The high-temperature Cp measurement results have been used to investigate regression models based on the Maier–Kelley and Khodakovsky equations for the temperature dependence of its isobaric heat capacity in the range from 298 to 875 K. The Debye characteristic temperature ΘD of PtS2 has been evaluated as a function of temperature. [ABSTRACT FROM AUTHOR]